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10-13-2009, 10:12 PM   #1
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Can someone do a experiment with their K7,16-45 and family for me?

Thinking about upgrading from K10D to K7 for one reason. I've decided, after much anguish, the K10D cannot focus on a group of people with darkish clothing on. If you have a K7, a 16-45/4 and a few family members handy, can you get them to adorn darkish clothing, line up so they take up the majority of the view (nothing facny, just a std line up in a row affair) in front of something like a bookcase or tree (if weather out side is nice) and snap a pic (obviously ensuring a focus point on them is used).

Report back if it focused on your subjects or the background.

Cheers, Nige

10-13-2009, 10:25 PM   #2
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Nige,
I don't even own a Pentax DSLR now, so I might not be the best person here to help you out.
However, if you put your camera on Center Point Focus, then focus, then re-compose without taking your finger off the shutter button you should be able to achieve that with any digital SLR.

I had no problems with that technique with my K100D, and I don't have any problems using my Sigma SD14 doing the same thing.

The only problems you may encounter is when it's getting too dark outside. Then if I remember correctly popping the flash up will pop the flash to help focus. Then just push the flash back down, if you don't want it.
10-13-2009, 10:30 PM   #3
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Stu's mentioned it - it's all about technique.
Once you appreciate how to use AF well, it is effective in most conditions, no matter what camera you use.
Extreme low light, all pre-K-7 cams will struggle, but otherwise, looking for a well contrasted area in the frame close to your subject in distance from the camera, then locking on that and recomposing is your best method.

Having the flash-assisted AF is also handy in these conditions, and if you have a modern external flash unit that has the spotbeam AF assist function, that's useful too.

But AF no matter what the camera has limitations - but knowing them as well as how to get the best out of the camera helps a great deal.

Last edited by Ash; 10-13-2009 at 10:40 PM.
10-13-2009, 10:41 PM   #4
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tried all that... including with 540 flash both bounced (my preference) and direct. I do find the on-board flash usually works ok (focus wise, the lighting just looks terrible) however it hasn't got the grunt to light a big enough area for what I want (say 8-10 peoples).

The camera locks focus (usually) but even though a whole person or 3 is taking up the area covered by the center AF point, it still decides to focus on something behind. I don't believe it's a back-focusing thing as I have many in-focus shots (in other scenerios). My 50-200 lens usually nails focus, but can't usually use that indoors.

10-13-2009, 11:03 PM   #5
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Why not then try manual focus?
OTOH, I have had consistent success with my 540 in low light, both focusing and adequately illuminating my indoor and outdoor scenes.

AF is not as fast using the spotbeam, but it is accurate AS LONG AS the subject AND the camera are reasonably still. Any movement after AF has locked means focus will not be quite right. In those situations, I don't even take the photo - I just relock and shoot as soon as it has locked.
10-13-2009, 11:49 PM   #6
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QuoteOriginally posted by Ash Quote
Why not then try manual focus?
A stupid belief that AF should work!!! I do have a split-prism (ebay special) focusing screen in it but I often forget to use it (like yesterday) or it's still hard to see in a darkish room. I've has decent results in just setting the focus half way between the infinity and the 2m mark (wish it had a longer throw!), set it at about f8 and fire away. The other issue is my wife uses this camera and she isn't capable of doing all this extra steps to get an in-focus pic.

I noticed in another thread that Vanbars have K7's on sale this week (need to ring and check if they still have any left) so I'll probably take my lens in one and try it out. If it fails this basic scenario it's going to cost me big time as I'm then going to try a D300s (I have some Nikkors that I can use although I'll still need a general purpose zoomy)

thanks for your interest and banter!

Cheers, Nige
10-14-2009, 08:46 AM   #7
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QuoteOriginally posted by HGMonaro Quote
The camera locks focus (usually) but even though a whole person or 3 is taking up the area covered by the center AF point, it still decides to focus on something behind.
Not if that person really takes up the whole area covered by the center point. the problem you are presumably seeing here is that the center AF point is *much* larger than the red square that appears in the viewfinder. It's closer to the size of the whole round center bracketed area. You can do some test by trying to focus on a black dot on a white piece of paper (with the dot off center in the viewfinder) to see just large the sensor is. You need to be careful to have your subject cover that entire area in order to be sure the camera will choose it and not the background.

FWIW, I often aim at the neck in situations like this, putting the head and body both within range of the sensor.
10-14-2009, 12:22 PM   #8
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Just do what I do and make sure everyone is nude.

10-14-2009, 01:16 PM   #9
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QuoteOriginally posted by c.r.brown Quote
Just do what I do and make sure everyone is nude.
Not necessarily something you want to do on your family shot for the x-mas card
10-16-2009, 11:11 PM   #10
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quick update... went and grabbed one of the Vanbar $1250 K7 specials today. Focusing seems greatly improved!!!!
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